Cystic fibrosis causes the body to produce thick secretions that affect the lungs and digestive tract. 1 in every 10 babies born with cystic fibrosis undergoes an operation within the first few days of life due to a bowel obstruction. Children and adults suffer from repeated chest infections and problems with pancreas function. The latter complication makes it difficult for cystic fibrosis sufferers to digest food. This can lead to malnutrition, poor growth, physical weakness and delayed puberty. In older patients insulin production can become deficient due to increasing pancreatic disease thus resulting in diabetes. Cystic fibrosis can also cause blockages of liver ducts. This occurs in approximately 8% of sufferers however the health risk is so severe that liver transplants are necessary. While the disease has serious effects on the gut, pancreas, liver and reproductive tract the effect it has on the lungs are the most severe. Repeated cycles of infection lead to continuous inflammation and damage to the lungs which ultimately leads to respiratory failure and death.
Cystic fibrosis is a genetic disease caused by a mutation within a single gene, CFTR (Cystic Fibrosis Trans-membrane Conductance Regulator). Thus by treating patients using gene therapy it is possible to treat the underlying cause of the disease and not the symptoms. Introduction of CFTR has been shown to correct the cystic fibrosis defect in vitro. Gene therapy has been tested on humans using viruses and liposomes as transfection vectors. Recombinant viruses used for gene transfer need to be able to infect both dividing and non-dividing cells, integrate into the host geneome and give long term gene expression. Of all of the viral vectors tested so far (adenovirus, retrovirus, adeno-associated virus and sendai virus) non have all of these features. Viral vectors used as gene delivery systems also have potential safety issues and are ineffective long term due to a triggering of the immune response. Similar transfection problems apply to a wide variety of genetic diseases.
The present invention addresses the need for a non-viral gene transfection agent which mitigates the disadvantages associated with recombinant viral vectors. Non-viral agents are non-infectious, relatively non-immunogenic, have low toxicity, can carry larger DNA plasmids and can be produced cheaply on a large scale. One type of agent is DNA coated magnetic particles.
Current magnetic based transfection systems have a low efficiency of transformation. The present inventors have developed a magnetic particle based delivery system which has surprisingly been shown to have a transformation efficiency 10 times greater than the current systems based on initial in vitro studies.